A miniature transducer designed for use in a medical imaging system catheter probe is disclosed. The transducer has an electric cavity and coaxial construction for preventing electric fields from being emitted or received by the transducers. The construction of the transducer enables two to be mounted very close to one another on a thin catheter probe, one for transmitting acoustic pulses and the other for sensing echoes in response to the acoustic pulses, for imaging extremely close targets. The transducers can be secured to the catheter probe in such a way as to substantially acoustically isolate one from the other.

A method of making the transducer by applying several electrically-conductive and insulating coatings and layers to a core in selected sequence so as to create a transducer having an electrical cavity, coaxial construction.

Patent
   4862893
Priority
Dec 08 1987
Filed
Feb 02 1988
Issued
Sep 05 1989
Expiry
Dec 08 2007
Assg.orig
Entity
Large
167
9
EXPIRED
1. A transducer comprising:
a ceramic substrate having a top surface, a bottom surface, a front surface, a back surface, a left side surface and a right side surface;
a first layer of electrically conductive material disposed on said top surface and said front surface of said substrate;
a piezoelectric device including a sheet of piezoelectric material, said sheet having one side electrically connected to and covering said first layer of electrically conductive material on said top surface of said substrate, said device further including an electrically conductive electrode on the other side of said sheet;
an inner conductor attached to and electrically connected with said first layer of electrically conductive material on said front surface of said substrate;
an insulative coating covering said inner conductor, said layer of electrically conductive material on said front surface, and said back, bottom, left side and right side surfaces of said substrate;
a drain wire wound on said insulative coating on said inner conductor and disposed against said insulative coating covering said substrate; and
an electrically-conductive coating covering said insulative coating on said front surface, back surface, bottom surface, left side surface, right side surface, and said drain wire, said electrically-conductive coating being electrically connected to the electrode provided on the other side of said piezoelectric sheet so that said substrate and said piezoelectric sheet are completely encased in electrically conductive material provided by said electrically conductive coating and said electrode provided on the other side of said piezoelectric sheet so as to electrically shield said substrate and said piezoelectric sheet.
2. The transducer according to claim 1, wherein the portion of said first layer of electrically conductive material disposed on said top surface of said substrate forms a second electrode of said piezoelectric device.
3. The transducer according to claim 1, wherein said first layer of electrically conductive material is a layer disposed on said top and front surfaces of said substrate so as to completely cover said top and front surfaces with said electrically conductive material.
4. The transducer according to claim 1, wherein said electrically conductive coating is of substantially uniform thickness of about 0.2 mil. inches thick.
5. The transducer according to claim 4, wherein said first layer of electrically conductive material is a metallic cladding.
6. The transducer according to claim 5, further including an electrically conductive adhesive for securing said inner conductor to the electrically conductive material on said front surface.
7. The transducer according to claim 6, wherein said electrically conductive adhesive is a silverfilled room temperature vulcanizing glue.
8. The transducer according to claim 1, wherein said insulative coating is a vinyl material.
9. The transducer according to claim 8, wherein said layer of vinyl has a thickness of about 0.001 inches.
10. The transducer according to claim 1, wherein said electrically conductive coating is an electrically conductive paint.
11. The transducer according to claim 10, wherein said electrically conductive paint is a silver-filled room temperature vulcanizing paint.
12. A transducer according to claim 1, wherein said sheet of piezoelectric material has an acoustic impedance that is substantially equal to the acoustic impedance of body fluids.
13. A transducer according to claim 12, wherein said sheet of piezoelectric material comprises a polyvinylidene fluoride foil.
14. A transducer according to claim 13, wherein said ceramic substrate is made of aluminum oxide.
15. A transducer according to claim 12, wherein said substrate is about 0.012 inches thick, about 0.028 inches wide and about 0.038 inches long.

This application is a continuation-in-part of co-pending application U.S. Application Ser. No. 129,830 filed Dec. 8, 1987 in the names of Michael Martinelli and Peter von Thuna (hereinafter referred to as the "Parent Application"), the latter application being a continuation-in-part of U.S. Application Ser. No. 856,621 filed Apr. 25, 1986 in the names of Michael Martinelli, Thomas Aretz, John Butterly and Stanley M. Shapshey, and now abandoned.

The present invention relates generally to electro-acoustical devices for converting electrical energy into acoustical energy and vice versa, and more particularly to a miniature transducer, an improved system utilizing such transducers for imaging internal features of various parts of a body and, a method of making such transducers.

Devices are known which use pulse-echo ultrasound to provide information regarding the thickness, configuration, composition and other characteristics of internal features of various parts of a body. Such a device is described, for instance, in U.S. Pat. No. 4,576,177 to Webster. However, specific problems are encountered when utilizing pulse-echo ultrasound to acquire information with sufficiently high resolution in extremely close range applications, such as acquiring information relating to the walls of coronary arteries.

More specifically, in known long range ranging systems, such as pulse-echo radar or sonar, a single electro-acoustical device is typically used for transmitting the sounding pulses and receiving the echoes. The device is switched between transmit and receive modes using a TR switch. The latter is designed to operate so as to minimize any interference during the receive mode caused by the excitation of the electro-acoustic device during the transmit mode. For example, the instant the device stops transmitting it may continue to ring. Accordingly, in order to receive any echo signals it is important that the device be allowed to stop ringing before the device is switched to the receiving mode. The TR switch can be operated quickly to quench the device at the termination of the transmit mode in order to switch the device to the receive mode. However, a finite time is nevertheless required to expire before the electro-acoustic device is sufficiently quiescent in order to operate in the receive mode without residual interference from the transmit mode. This finite time, called "dead space", thus creates a minimum time the receiver must be turned off following the end of the transmit mode. In other words, the target distance must be sufficiently large so that echoes are not received by the electro-acoustic device until after the time of the dead space has elapsed. The dead space therefore creates a minimum target distance at which the ranging device will operate without cross interference between the two modes and without a loss of information. This is usually not a problem for typical radar and sonar applications where target distances are well beyond the minimum distance required.

In an effort to improve short range performance, some short range pulse-echo ranging systems have resorted to using separate transmitter and receiver devices. The amount of excitation from the transmit pulse resident in the receive channel is naturally reduced by the physical isolation of the two (often by physically spacing one a relatively large distance from the other) and, hence, the switching need not be so complete as is the case when a single device is used to transmit and receive. Additional improvements can be achieved by utilizing improved materials which exhibit reduced ringing. For example, as described hereinafter, certain plastic materials have been found particularly useful in medical imaging applications because of the reduced acoustic impedance of such materials relative to known crystalline materials. However, such systems are still range limited by the required dead space, and the physical separation of the two transmitter and receiver devices. Therefore, until the present invention the use of separate transmitter and receiver devices for pulse-echo ultrasonic acquisition of information regarding very close range targets, such as the walls of coronary arteries, has been impractical.

More specifically, the system disclosed in the Parent Application comprises a catheter probe that is adapted to be inserted into a part of a body, and is particularly good at providing relatively high resolution imaging data of an relatively small, predetermined portion of the body, such as a small section of a coronary artery (the catheter may also be adapted to deliver laser energy to the interior of the body part for modifying internal features thereof, e.g., removing plaque deposits from a coronary artery). A transducer assembly is attached to the distal end of the catheter for emitting and receiving acoustic pulses used in generating imaging information. Sets of imaging data are created by moving the catheter axially along and notationally about its axis, within the body section of interest, through a series of imaging locations, while the transducer assembly is actuated to emit a train of acoustic pulses and responsively receive a series of acoustic echoes at each imaging location. By also continuously sensing the location of the catheter, and relating the set of data to the respective location where it was generated, an image of the internal features of the body part may be generated.

It is clear that the target being imaged by the system disclosed in the Parent Application is extremely close to the transducer assembly. In fact the transducer assembly is frequently almost in contact with the targeted surfaces, such as the inner surface of the wall of an artery. At such close range, relying on standard radar and sonar techniques of allowing the required time of dead space to transpire after the transmit mode and before switching to a receiving mode is inadequate since the target ranges are well below the minimum range for the dead space required and imaging data will be lost during this time. Utilizing two transducer devices, one for transmitting and one for receiving, does not alone overcome the problem since the two devices must be mounted on the end of a catheter extremely close to one another. Because of the close proximity between the two devices, sufficient dead space still must be provided to prevent acoustic interference, such as acoustic cross talk, between the transmitting device and receiving device, as for example when the transmitting device is ringing following the generation of an acoustic pulse. In fact, because of the close proximity of the two, certain electrical interference problems can occur between the transmitting and receiving devices which do not occur with a single device, such as capacitive and inductive coupling between the two devices.

It is a principal object of the present invention to provide an improved electro-acoustic device adapted to overcome or substantially reduce the above-noted problems.

It is another object of the present invention to provide an improved electro-acoustic device capable of operating as a transmitting or receiving device in a close range ranging system such as described in the Parent Application.

Still another object of the present is to provide an improved electro-acoustic device constructed and mounted to be substantially acoustically and electrically isolated, so that two such devices can be used respectively as transmitting and receiving devices in relatively close proximity to one another for use in a relatively close range ranging system, such as the system described in the Parent Application.

Yet another object of the present invention is to provide an improved electro-acoustic device constructed and mounted so as to substantially reduce the amount of ringing of the device following the transmission of an acoustic pulse, and substantially prevent the generation of stray electric fields.

And still another object of the present invention is to provide a method of making such a transducer.

And yet another object of the present invention is to provide a catheter probe including a transmitter electro-acoustic transducer and a receiver electro-acoustic transducer so that extremely close objects can be imaged in accordance with the system described in the Parent Application;

And still another object of the present invention is to provide such a catheter of the type described in the Parent Application in which the acoustic pulses are transmitted and received by a pair of transducer devices which are substantially acoustically and electrically isolated from one another.

These and other objects are achieved by a novel miniature electro-acoustic transducer, a novel method of making the transducer, and an improved catheter probe having a pair of such transducers for generating acoustic information used to image internal features of a body part.

The transducer has a novel coaxial and closed electrical cavity construction for electrically shielding the transducer.

The transducer is designed for use in pairs on an imaging system catheter of the type described in the Parent Application. A pair of the transducers of the present invention are mounted on the distal end of the catheter in such a manner so as to minimize acoustic interference between the transducers.

Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the processes involving the several steps and the relation and order of one or more of such steps with respect to each of the others, the product possessing the features, properties and relation of components, and the apparatus possessing the construction, combination of elements and arrangement of parts, all of which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, wherein:

FIG. 1 is a perspective view of the preferred embodiment of the transducer of the present invention, partially broken away to expose internal features thereof;

FIGS. 2-8 are schematic, perspective views of successive intermediate products provided in successive steps of the preferred process of fabricating the transducer shown in FIG. 1;

FIG. 9 is a perspective view of the tip portion of the distal end of the catheter of the type used in the imaging system described in the Parent Application, and incorporating the present invention;

FIG. 10 is a side elevation view of the tip portion of the catheter shown in FIG. 9.

The configuration and relative dimensions of the various layers and elements illustrated in the drawings have been modified for clarity of illustration and description. In the drawings the same reference numerals are used to refer to the same and like parts.

The preferred embodiment of the transducer of the present invention is illustrated in FIG. 1. The transducer comprises an inner core or substrate 20 and a piezoelectric device 32 disposed on the substrate. The transducer is constructed so that it is electrically shielded such that two such transducers are capable of operating adjacent one another, with one transducer operating as a transmitting device and the other as a receiver device without significant electrical interference. Further, as will be more evident hereinafter, the two transducers can be suitably mounted on a catheter 100 (as described in greater detail hereinafter with respect to FIGS. 9 and 10) so that the two transducers are substantially acoustically isolated from one another.

More specifically, substrate 20 is preferably made from a suitable ceramic material, such as alumina, i.e., aluminum oxide. The substrate is shown in the drawings as a rectangular block or brick comprising a front surface 22 (FIGS. 1 and 2), a top surface 24 (FIG. 2), a left side surface 26 (FIG. 3), a right side surface 28 (FIG. 3), a bottom surface (not shown) opposite top surface 24, and a rear surface (not shown) opposite front surface 22. It should be appreciated, however, that the exact configuration of the substrate can vary depending upon the application for which the transducer is intended to be used.

Since the transducer is preferably designed for use on a catheter of an imaging system of the type described in the Parent Application, the size of the transducer must be relatively small. Where the imaging system is designed to image selected portions of coronary arteries, the substrate 20 is dimensioned so that it is thick enough to function as an acoustic reflector for the piezoelectric device 32. In the preferred embodiment where the piezoelectric device is a polymer piezoelectric device (as described hereinafter), the substrate is dimensioned on the order of about 0.028 inches wide, 0.038 inches long, and 0.012 inches thick, although I believe, at least in the case of alumina, the substrate can be made even thinner. The minimum thickness of the substrate is limited by the acoustic reflectivity of the substrate material for the piezoelectric device 32 and the acoustic impedance mismatch between the two. For alumina at the acoustic frequency of interest (in the megahertz region), the minimum thickness is believed to be about 0.006 inches thick at which dimension the substrate still adequately functions as a reflector for acoustic energy generated by the piezoelectric device 32 disposed on the substrate. Decreasing the thickness to less than 0.006 inches reduces the ability of the substrate to reflect the acoustic energy to the point where a substrate of 0.003 inch thickness will cease to function as an adequate reflector so that substantially all of the acoustic energy transmitted by the device 32 downwardly will be transmitted through the substrate. As discussed hereinafter, the relatively small size of the transducer is made possible because of the material from which the piezoelectric device 32 is made, and more particularly, its relatively close impedance match to that of body fluids.

In the preferred embodiment of the invention the front surface 22 and top surface 24 are coated with an electrically conductive coating 30, preferably in the form of a metallized cladding, such as vapor deposited gold or a heat sintered metal cladding (such as granulated nickel), so as to provide an electrical connection between the front surface and the top surface. Preferably, coating 30 is about 0.2 mil. inches thick although the thickness can vary depending upon the material and application of the transducer.

In one embodiment of the present invention a sheet or coating 33 of dielectric material having piezoelectric characteristics, and forming the center dielectric material of the piezoelectric device 32, is secured to coating 30 on top surface 24. In sheet form the dielectric material may be secured, for example, with an electrically conductive epoxy, so that coating 30 forms the bottom electrode of the piezoelectric device. Alternatively, where the piezoelectric material is of a type that can be applied as a coating, e.g., such as the materials described below, the sheet can be deposited as a coating of substantial uniform thickness over the coating 30. As will be more evident hereinafter, the top electrode of the piezoelectric device 32 is provided when the outer coating 54 of electrically conductive material is provided over the top surface of the sheet 33.

Sheet 33 is made of a material which preferably has an acoustic impedance that closely matches the acoustic impedance of body fluids and water, but provides a substantial impedance mismatch with the material of the substrate. Certain plastic or polymer piezoelectric materials, such as polyvinylidene fluoride (PVDF) or similar copolymer materials such as PVF2 are satisfactory. The latter materials have an acoustic impedance (defined as the complex ratio of the sound pressure on a given surface to the sound flux through that surface) of about 4.3 million Rayleighs (4.3 x 106 kg/(m2 s)), while the acoustic impedance of blood and other body tissues is in the order of 1.5 million Rayleighs. As described hereinafter in greater detail with respect to FIG. 9, the final match between these two is accomplished by a one-quarter wave anti-reflective intervening layer of plastic film disposed over the top of the transducer. This is substantially close when one considers that the acoustic impedance of a PZT crystal material has an acoustic impedance in the order of 30.0 million Rayleighs. The reflectivity of the substrate is also a function of the acoustic impedance mismatch between the substrate and the piezoelectric device Alumina has an acoustic impedance of about 40 million Rayleighs which provides a greater mismatch, and therefore is more reflective, with the polymeric materials described, then would be provided by a PZT crystal material. For a description of the advantages of polymer piezoelectric materials over ferro-electric ceramic materials in transducers for medical ultrasound applications, see generally Lancee, C. T.; Souquet, J.; Ohigashi, H.; and Bom, N.; " Ferro-electric Ceramics Versus Polymer Piezoelectric Materials", presented as a paper during the Fifth Symposium on Echocardiology held in Rotterdam, the Netherlands, in 1983. It should be appreciated that the piezoelectric device 32 can be preformed by providing a sheet 33 with electrodes previously formed respectively on its top and bottom surfaces before it is secured to the coating 30. For example, a 52 micron thick polyvinylidene fluoride (PVDF) foil of the type manufactured and sold by Pennwalt Corporation of King of Prussia, PA, under the tradename KYNAR Piezo Film, would be satisfactory.

The inner conductor or core wire 34 of coaxial line 36 is preferably attached to front surface 22 using an electrically-conductive glue 38, e.g. a silver-filled room temperature vulcanizable (RTV) glue, so as to be electrically connected t coating 30 on front surface 22. The wire 34 is preferably mounted to extend substantially parallel with the top and bottom surfaces of the transducer and normally to the left and right side surfaces of the transducer. In the embodiment of the transducer used in the imaging system of the Parent Application, core wire 34 is about 0.001 inch in diameter, and because of its thinness is preferably made of a high strength electrically conductive material such as the nickel-copper alloy of the type manufactured under the trademark Monel by the International Nickel Co. Inc. of Huntington, WV, on the nickel-chromium-aluminum-copper alloy of the type manufactured under the trademark Evanohm by Wilbur B. Driver Company, Newark, NJ., or other suitable, high strength electrically-conductive material. The electrically conductive glue 38 is applied only on front surface 22, and care is taken so that the glue does not extend into contact with piezoelectric sheet 33 (or the upper electrode where the device is preformed before being mounted on the top of the substrate).

An electrically insulating conformal coating 50 covers core wire 34, glue 38, front surface 22, left side surface 26, right side surface 28 and the back and bottom surfaces of core 20. Again care is taken so that none of the coating 50 contacts piezoelectric sheet 33 (or piezoelectric device 32, where the latter is preformed before being applied to the substrate). Coating 50 is approximately 0.003 inches thick when applied to the core wire 34 and about 0.001 inches thick when applied to the remaining surfaces around the substrate. The coating 50 is preferably made from a vinyl material, but other conformal materials having suitable insulative properties may also be satisfactorily employed.

An electrically conductive drain wire 52, made for example of gold, is wrapped around coating 50 on core wire 34 and is attached by suitable means to the insulative coating 50 on front surface 22. Drain wire 52 is preferably about 0.0007 inches in diameter, although the size of the wire can vary.

An electrically-conductive coating 54 completely covers insulative coating 50, drain wire 52, as well as the piezoelectric sheet 33 (where the top surface of the sheet is exposed) so as to completely encapsulate the entire assembly with an electrical conductor. Where device 32 is preformed with electrodes prior to mounting the device on the substrate, the upper exposed surface of the device will already be provided with an electrically conductive material so that coating 54 need only extend over the top edges of the front, rear, left and right side surfaces of the transducer so as to electrically contact the edge portions of upper exposed electrode of piezoelectric device 32. Thus, conductive coating 54 covers drain wire 34 and insulative coating 50 on core wire 34 (so as to form the outer conductor of the coaxial line 36). The conductive coating 54 (together with the upper electrode of the device 32) also encases the substrate and piezoelectric sheet 33 so as to form an electric shield as well as a conductor for providing an electrical path between the top side of the sheet 33 of the piezoelectric device 32, and the outer conductor of the coaxial line 36. Conductive coating 54 is preferably made from a silver-filled, RTV paint, and is preferably less than 0.001 inches thick, although other materials and thicknesses may be utilized.

The construction of the transducer is that of an electrical cavity fed by a co-axial conduction line. The combination, when functioning as a transmitter, will contain all electromagnetic fields introduced by way of the co-axial arrangement to the inside of the co-axial line and the electrical cavity. When the combination functions as a receiver, all external electromagnetic fields will be excluded from the inside of both the electrical cavity and the co-axial line, and thus, will exhibit an immunity to incidental fields. When two such transducers are utilized together, one as a transmitter and the other as a receiver, as is contemplated in accordance with at least one aspect of the present invention, the combined effect of driver field retention or trapping and exterior field rejection results in extremely low electrical and magnetic cross talk between transmitter and receiver.

To use the transducer shown in FIG. 1 in the transmit mode of the imaging system described in the Parent Application, an electrical excitation voltage, preferably in the form of a train of pulses, is applied between the electrodes provided in contact with top and bottom surfaces of the piezoelectric sheet 33 (in the embodiment illustrated the top electrode is provided by the conductive coating 54 covering the sheet 33, while the bottom electrode is provided by the coating 30 provided between the top surface 24 of the substrate 20 and the bottom surface of the piezoelectric sheet 33), wherein one electrical path for applying the excitation voltage is formed by the core wire 34 of coaxial line 36, through conductive glue 38 to coating 30 on front surface 22, and in turn to coating 30 on top surface 24 (which directly contacts the lower side of the sheet 33 or directly contacts the lower electrode of the device 32, where the latter is preformed before being mounted to the substrate). The other conductive path for applying the electrical excitation voltage is provided through conductive coating 54 over the outer conductor of the coaxial line 36 and directly to the top surface of the piezoelectric device 32. In accordance with the well known operating characteristics of piezoelectric materials, piezoelectric sheet 33 converts electrical energy from the excitation voltage applied to the sheet to mechanical energy. More specifically, as is also well known, the application of an excitation voltage to piezoelectric material causes the latter to mechanically distort so as to generate an ultrasonic signal in a direction normal to top surface 24.

The drain wire 52 provides a more highly conductive ground path than would be provided by the coating 54 alone. The wire 52 provides longitudinal conductivity while coating 54 provides lateral conductivity.

When the transducer is operated in the receive mode, acoustic pulses which contact piezoelectric device 32 slightly distort the device causing potential to develop across the top and bottom electrodes (formed in the embodiment shown by coatings 54 and 30, respectively). As is well known, the potential varies with the strength of the acoustic pulse. The potential generated by piezoelectric device 32 is sensed through one conductive path defined by the coating 30 on top surface 24 to side surface 22 and through conductive glue 38 to core wire 34, and through the other conductive path defined by the conductive coating 54. The potential will be proportional to the acoustic pulse sensed. By connecting core wire 34 and the outer coating 54 of the coaxial line 36 to a response circuit (not shown) the sensed voltage can be amplified and processed as described in the Parent Application.

In connection with the following description of the method of making the transducer of the present invention, reference should be made to FIGS. 2-8.

A core or substrate 20 is provided as the starting material as shown in FIG. 2. The substrate is cut or otherwise formed to the required size.

In the second step, as illustrated in FIG. 3, front surface 22 and top surface 24 are provided with a continuous electrically conductive layer 30. As noted above, a metallized cladding may be used to form coating 30. Preferably, the coating is applied to a thickness of about 0.2 mil inches.

For the third step, as illustrated in FIG. 4, where sheet 33 of piezoelectric material is provided in sheet form, it is applied to the layer 30 provided on top surface 24 using an electrically conductive epoxy to secure the bottom surface of the sheet 33 to the top surface of the layer 30. Alternatively, the material may be applied directly to coating 30 as a coating of piezoelectric material using well known deposition techniques. Where device 32 is preformed with electrodes such as the PVDF foil described above, the bottom electrode is secured to the layer 30 with a suitable electrically conductive material, such as an electrically conductive epoxy. As discussed above, piezoelectric device has an acoustic impedance which is close to that of water and body fluids. Piezoelectric device 32 is preferably sized to cover the entire top surface 24 of the substrate when it is secured to the coating 30 on that surface.

As the fourth step, as illustrated in FIG. 5, one end of core wire 34 is attached to electrically conductive coating 30 on front surface 22 using an electrically conductive glue 38. It is important that glue 38 be applied to front surface 22 so as not to extend into contact with piezoelectric sheet 33, or when device 32 is preformed before being mounted on the substrate, into contact with the upper surface of the piezoelectric device.

In the fifth step, as illustrated in FIG. 6, core wire 34 and the entire transducer, except for piezoelectric sheet 33 (or device 32), is covered with an electrically insulating conformal coating 50, e.g., a vinyl coating.

At step six, as illustrated in FIG. 7, gold drain wire 34 is wrapped around the insulative coating 50 on core wire 34 and the end of the wire adjacent the transducer is attached to insulative coating 50 on front surface 22 using an electrically conductive cement.

In the final step, as illustrated in FIG. 8, a layer 54 of electrically-conductive paint is applied to all four sides and the bottom of the transducer, to insulative coating 50 on core wire 34, to the drain wire 52 wrapped around the coated core wire, and where sheet 33 is applied without a top electrode, to the entire top surface of the sheet 33. Where the piezoelectric device 32 is preformed, layer 54 is applied to all of the surfaces except the upper electrode, but is applied with respect to that electrode so as to extend over the side surfaces of the transducer onto peripheral edge portions of the upper electrode so as to electrically connect the electrically-conductive layer 54 on the sides and bottom of the transducer with piezoelectric device 32 and create the electrical cavity.

Known integrated circuit chip and miniature electronic component fabrication techniques may be satisfactorily employed in the above-described method of manufacturing the transducer of the present invention. For instance, electrically-conductive layers 30 and 54 and insulative layer 50 may be applied using known mask and spray techniques. Piezoelectric sheet 33 may be applied using known vacuum workpiece positioning systems.

Referring next to FIGS. 9 and 10, in accordance with another aspect of the present invention, a catheter probe 100 includes a pair of the transducers of the present invention and is designed for use in a system for imaging internal features of a body part, such as the system described in the Parent Application.

The catheter probe 100 of the present invention comprises an flexible tubular body having a distal end 104 and a flat surface 106 for supporting each transducer 110 and 112. The flat surface extends along a portion of the length of body and is formed adjacent distal end 104. As best seen in FIG. 10, flat surface 106 is treated, preferably when initially formed, to provide a roughened surface so as to create dead air spaces between the catheter and each transducer 110 and 112.

As described in the Parent Application, a loop of wire 108 is attached to the body at the distal end 104. Loop 108 is provided as an antenna for detecting magnetic reference signals used in establishing the position of the distal end of the catheter probe 100 inside the body part being imaged.

Catheter probe 100 further comprises transmit transducer 110 and receive transducer 112, each constructed as described with respect to FIGS. 1-8. The two transducers are positioned on probe 100 so the bottom surfaces of the transducers rest on the roughened surface formed on flat surface 106. Where the catheter body is formed of a high modulus nylon, such as the nylon material sold under the trademark Zitel 42, the roughened surface 106 can be mechanically formed, for example, by using a fine grain sand paper to rub the flat surface so as to create randomly dispersed burrs or irregular cuts on the surface with hanging fragments at least in the area which will support the transducers 110 and 112. Because of the close range of the target, the transducers 110 and 112 are positioned adjacent to, but spaced apart slightly, e.g., about 0.006 inches, from one another. The coaxial line 36a provides the excitation voltage to the transmit transducer 110, while coaxial line 36b provides signals representative of the acoustic energy sensed by receive transducer 112. Coaxial wires 36a and 36b are positioned to extend along the surface of the body, away from distal end 104.

Probe 100 also comprises one or more optical waveguides 120 for transmitting laser energy toward distal end 104 to a position adjacent receive transducer 112. A mirror 122 is positioned between transducer 112 and the output ends 124 of waveguides 120 for directing the laser energy transmitted by waveguides 120 so as to travel in a direction substantially parallel to the direction of an axis normal to the upper surface of the transducer 112, transverse to the axis of the catheter.

In order to secure the two transducers in place on the catheter probe, the entire end portion of catheter probe 100, including the two transducers, is wrapped in a thin film 2. The selection of material for the film 102 should have an acoustic impedance which closely approximates the geometric mean of the acoustic impedances of the transducer piezoelectric device 32 and the bodily fluids in contact with the film in order to improve the acoustic coupling between the device 32 and the fluids. The foregoing is easily accomplished with any one of several plastic films, with polyethylene being preferred. The plastic film functions as a one-quarter wave anti-reflective intervening layer of plastic material between each transducer and the body tissues disposed over the transducer at the particular location of the device. The preferred polyethylene film can be provided with a coating of suitable gummed adhesive on its inner surface so as to ensure the film remains in a wrapped condition.

A wrap 128 covers the remaining portions of the catheter end not covered by the film 102 and therefore does not cover the transducers.

Coaxial lines 36a and 36b, antenna loop 108, and optical waveguides 120 are encased in film 128 and extend away from distal end 104 of probe 100 extending along the body 102 of the catheter. These wires and optical fibers are enclosed as a bundle in a suitable casing. This encased bundle is connected to a control device (not shown) for generating the excitation voltage supplied over coaxial wire 36a to transmit transducer 110, for receiving the response signal from receive transducer 112 carried over coaxial line 36b, for generating the laser energy transmitted over optical waveguides 120, and for receiving signals over wire ends 109 from wire loop 108.

It is important that transducers 110 and 112 be positioned as close to one another as possible so that the receive transducer 112 is positioned to receive echo pulses from relatively close targets in response to acoustic pulses generated by the transmit transducer 110. The electrical cavity construction of the transducer of the present invention permits transducers 110 and 112 to be mounted in side-by-side configuration, as the electrical cavity casing around the transducers substantially prevents electromagnetic fields from leaking out or entering the transducers. As such, the transducers are electromagnetically isolated from one another, with the result that there is little or no electromagnetic interference between transducers 110 and 112.

It is equally important that transducers 110 and 112 be acoustically isolated from one another. Because acoustic cross talk arrives later in time than electrical cross talk, the acoustic cross talk can arrive at the receiving transducer at the same time as the echo data signals and therefore make it even more difficult to process the latter signals. By roughening the flat surface 106, the transmit and receive transducer 110 and 112 are mounted so as to be substantially acoustically isolated from one another because the roughened surface provides sufficient dead air space between the bottom surface of each transducer and the surface 106 so as to substantially acoustically dampen any acoustic signals which might be transmitted between the two transducers through the body 102. The acoustic dampening virtually eliminates any detrimental acoustic cross talk between the transducers.

Catheter probe 100 is used in substantially the same manner as the catheter probe of the imaging system disclosed in the Parent Application. Thus, attention is directed to the Parent Application for a complete description of the manner in which probe 100 is used. Briefly, however, the distal end of the catheter probe 100 is inserted in a selected body part, e.g., a coronary artery, until the probe is positioned at an area of interest. The signals received on wire loop 108 are used in determining the radial position of probe 100. The receive transducer senses the axial position of the probe. Acoustic pulses are transmitted from transmit transducer 110 and the associated echo pulses are sensed by receive transducer 112. Pursuant to the information received from receive transducer 112 and wire loop 108, an image of the internal features of the body part can be generated. Using this image, laser energy can transmitted along optical waveguide 120, and folded at mirror 122 so as to selectively radiate preselected portions of the portion of the body under investigation. This laser energy can be used, for instance, to burn away plaque deposits inside a coronary artery.

A significant advantage of the transducer of the present invention is that two of the transducers can be positioned adjacent one another without substantially electromagnetically interfering with one another. The electrical isolation provided by the electrical cavity and coaxial construction of the transducers greatly reduces or eliminates electrical cross talk between the transducers. As such, the transducer of the present invention is highly suited for use, in side-by-side configuration, particularly for close range ranging systems such as the system disclosed in the Parent Application. Further, by mounting the transducers on a roughened surface of the catheter, the two transducers can be substantially acoustically isolated from one another so as to substantially reduce the effects of acoustical cross-talk between the two transducers so that the two transducers 110 and 112 can be mounted very close to one another without interfering with one another.

Because the piezoelectric material used for piezoelectric sheet 33 is substantially acoustically matched to the body fluids, the transducers can be made miniature in size so as to fit on the distal end of the catheter probe. Consequently, the use of miniature transducers makes the use of the probe as part of the imaging system described in the Parent Application practical. The method of manufacturing the transducer of the present invention is designed to permit rapid and efficient fabrication of the miniature transducer, transducer for example, having miniature external dimensions in the range of 0.012" (thickness) × 0.028" (width) × 0.038" (length-along the length of the catheter). It is believed that the transducer can be made even smaller than these dimensions with, for example, improved copolymer materials for sheet 33 providing an even closer match in acoustic impedance (so as to allow a decrease in the thickness dimension) and increased signal strength per unit area (so as to allow a decrease in the thickness dimension).

An important advantage of the catheter probe of the present invention, as compared to known ultrasonic probes having a single transducer for transmitting and receiving acoustic pulses, is that the present catheter probe will provide accurate imaging data of internal body features at extremely close range, where in some cases the outer surface of the film 128 above the upper surface of the piezoelectric device 32, directly contacts a surface of interest. With single ultrasonic transducer probes, the minimum range of the devices is typically between about a few millimeters to 10 centimeters or so.

Since certain changes may be made in the above product, method and apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted in an illustrative and not in a limiting sense.

Martinelli, Michael A.

Patent Priority Assignee Title
10070801, Jul 10 2008 Covidien LP Integrated multi-functional endoscopic tool
10096126, Jun 03 2008 Covidien LP Feature-based registration method
10154798, Apr 08 2009 Covidien LP Locatable catheter
10285623, Jun 06 2008 Covidien LP Hybrid registration method
10321803, May 01 2005 Covidien LP System and method for image-based alignment of an endoscope
10368840, Aug 03 2017 Seiko Epson Corporation Ultrasonic apparatus
10383509, Sep 15 2003 Covidien LP System of accessories for use with bronchoscopes
10390686, Sep 27 2007 Covidien LP Bronchoscope adapter and method
10418705, Oct 28 2016 Covidien LP Electromagnetic navigation antenna assembly and electromagnetic navigation system including the same
10426555, Jun 03 2015 Covidien LP Medical instrument with sensor for use in a system and method for electromagnetic navigation
10446931, Oct 28 2016 Covidien LP Electromagnetic navigation antenna assembly and electromagnetic navigation system including the same
10478092, Jun 06 2008 Covidien LP Hybrid registration method
10478254, May 16 2016 Covidien LP System and method to access lung tissue
10517505, Oct 28 2016 Covidien LP Systems, methods, and computer-readable media for optimizing an electromagnetic navigation system
10517566, Sep 30 2013 Seiko Epson Corporation Ultrasonic device, ultrasonic probe, electronic equipment, and ultrasonic image device
10582834, Jun 15 2010 RIOJA LLC; Covidien LP Locatable expandable working channel and method
10597178, Jan 18 2006 Medtronic Navigation, Inc. Method and apparatus for providing a container to a sterile environment
10615500, Oct 28 2016 Covidien LP System and method for designing electromagnetic navigation antenna assemblies
10638952, Oct 28 2016 Covidien LP Methods, systems, and computer-readable media for calibrating an electromagnetic navigation system
10674936, Jun 06 2008 Covidien LP Hybrid registration method
10722311, Oct 28 2016 Covidien LP System and method for identifying a location and/or an orientation of an electromagnetic sensor based on a map
10743748, Apr 17 2002 Covidien LP Endoscope structures and techniques for navigating to a target in branched structure
10751126, Oct 28 2016 Covidien LP System and method for generating a map for electromagnetic navigation
10792106, Oct 28 2016 Covidien LP System for calibrating an electromagnetic navigation system
10898153, Mar 01 2000 Medtronic Navigation, Inc. Multiple cannula image guided tool for image guided procedures
10912487, Jul 10 2008 Covidien LP Integrated multi-function endoscopic tool
10952593, Jun 10 2014 Covidien LP Bronchoscope adapter
10980400, Sep 27 2007 Covidien LP Bronchoscope adapter and method
11006914, Oct 28 2015 Medtronic Navigation, Inc. Apparatus and method for maintaining image quality while minimizing x-ray dosage of a patient
11074702, Jun 03 2008 Covidien LP Feature-based registration method
11160617, May 16 2016 Covidien LP System and method to access lung tissue
11219489, Oct 31 2017 Covidien LP Devices and systems for providing sensors in parallel with medical tools
11234611, Jul 10 2008 Covidien LP Integrated multi-functional endoscopic tool
11241164, Jul 10 2008 Covidien LP Integrated multi-functional endoscopic tool
11331150, Oct 28 1999 Medtronic Navigation, Inc. Method and apparatus for surgical navigation
11672604, Oct 28 2016 Covidien LP System and method for generating a map for electromagnetic navigation
11684491, Jan 30 2003 Medtronic Navigation, Inc. Method and apparatus for post-operative tuning of a spinal implant
11707363, Jan 30 2003 Medtronic Navigation, Inc. Method and apparatus for post-operative tuning of a spinal implant
11759264, Oct 28 2016 Covidien LP System and method for identifying a location and/or an orientation of an electromagnetic sensor based on a map
11783498, Jun 03 2008 Covidien LP Feature-based registration method
11786314, Oct 28 2016 Covidien LP System for calibrating an electromagnetic navigation system
11786317, May 16 2016 Covidien LP System and method to access lung tissue
11801024, Oct 28 2015 Medtronic Navigation, Inc. Apparatus and method for maintaining image quality while minimizing x-ray dosage of a patient
5196006, Apr 25 1989 Summit Technology, Inc. Method and apparatus for excision endpoint control
5269291, Dec 10 1990 Coraje, Inc. Miniature ultrasonic transducer for plaque ablation
5470330, Dec 07 1984 Spectranetics; THE SPECTRANETICS CORPORATION Guidance and delivery system for high-energy pulsed laser light
5474072, Oct 29 1993 NeoVision Corporation Methods and apparatus for performing sonomammography
5479927, Oct 29 1993 NeoVision Corporation Methods and apparatus for performing sonomammography and enhanced x-ray imaging
5505088, Aug 27 1993 Stellartech Research Corporation Ultrasound microscope for imaging living tissues
5520189, Jul 13 1990 CORAJE, INC Intravascular ultrasound imaging guidewire
5577507, Nov 21 1994 General Electric Company Compound lens for ultrasound transducer probe
5660185, Apr 13 1995 NeoVision Corporation Image-guided biopsy apparatus with enhanced imaging and methods
5810009, Sep 27 1994 Kabushiki Kaisha Toshiba Ultrasonic probe, ultrasonic probe device having the ultrasonic probe, and method of manufacturing the ultrasonic probe
5820552, Jul 12 1996 United States Surgical Corporation Sonography and biopsy apparatus
5833627, Apr 13 1995 United States Surgical Corporation Image-guided biopsy apparatus and methods of use
5851180, Jul 12 1996 United States Surgical Corporation Traction-inducing compression assembly for enhanced tissue imaging
5938613, Oct 29 1993 United States Surgical Corporation Methods and apparatus for performing sonomammography and enhanced X-ray imaging
5983123, Oct 29 1993 United States Surgical Corporation Methods and apparatus for performing ultrasound and enhanced X-ray imaging
6027457, Jun 18 1998 United States Surgical Corporation Apparatus and method for securing tissue during ultrasound examination and biopsy
6104944, Nov 17 1997 SURGICAL NAVIGATION TECHNOLOGIES, INC System and method for navigating a multiple electrode catheter
6491702, Apr 21 1992 Sofamor Danek Holdings, Inc. Apparatus and method for photogrammetric surgical localization
6585763, Oct 14 1997 Pacesetter, Inc Implantable therapeutic device and method
6892090, Aug 19 2002 Surgical Navigation Technologies, Inc. Method and apparatus for virtual endoscopy
6920347, Apr 07 2000 Medtronic Navigation, Inc Trajectory storage apparatus and method for surgical navigation systems
6947786, Feb 28 2002 Medtronic Navigation, Inc Method and apparatus for perspective inversion
6968224, Oct 28 1999 Surgical Navigation Technologies, Inc. Method of detecting organ matter shift in a patient
6990368, Apr 04 2002 Medtronic Navigation, Inc Method and apparatus for virtual digital subtraction angiography
7007699, Oct 28 1999 SURGICAL NAVIGATION TECHNOLOGIES, INC Surgical sensor
7085400, Jun 14 2000 Surgical Navigation Technologies, Inc. System and method for image based sensor calibration
7130676, Aug 20 1998 Sofamor Danek Holdings, Inc. Fluoroscopic image guided orthopaedic surgery system with intraoperative registration
7174202, Jan 27 1993 British Telecommunications Medical navigation apparatus
7217276, Apr 20 1999 Surgical Navigational Technologies, Inc. Instrument guidance method and system for image guided surgery
7294913, Mar 18 2004 Chase Corporation Cathodic lead insulator
7313430, Aug 28 2003 Medtronic Navigation, Inc. Method and apparatus for performing stereotactic surgery
7366562, Oct 17 2003 SURGICAL NAVIGATION TECHNOLOGIES, INC Method and apparatus for surgical navigation
7542791, Jan 30 2003 Medtronic Navigation, Inc. Method and apparatus for preplanning a surgical procedure
7567834, May 03 2004 Medtronic Navigation, Inc Method and apparatus for implantation between two vertebral bodies
7570791, Apr 25 2003 Medtronic Navigation, Inc Method and apparatus for performing 2D to 3D registration
7599730, Nov 19 2002 Medtronic Navigation, Inc Navigation system for cardiac therapies
7606613, Mar 23 1999 Medtronic Navigation, Inc Navigational guidance via computer-assisted fluoroscopic imaging
7630753, Feb 28 2002 Medtronic Navigation, Inc. Method and apparatus for perspective inversion
7636595, Oct 28 2004 Medtronic Navigation, Inc. Method and apparatus for calibrating non-linear instruments
7657300, Oct 28 1999 Medtronic Navigation, Inc. Registration of human anatomy integrated for electromagnetic localization
7660623, Jan 30 2003 Medtronic Navigation, Inc. Six degree of freedom alignment display for medical procedures
7697972, Nov 19 2002 Medtronic Navigation, Inc Navigation system for cardiac therapies
7751865, Oct 17 2003 Medtronic Navigation, Inc. Method and apparatus for surgical navigation
7763035, Dec 12 1997 Medtronic Navigation, Inc. Image guided spinal surgery guide, system and method for use thereof
7797032, Oct 28 1999 SURGICAL NAVIGATION TECHNOLOGIES, INC Method and system for navigating a catheter probe in the presence of field-influencing objects
7818044, Oct 17 2003 Medtronic Navigation, Inc. Method and apparatus for surgical navigation
7831082, Jun 14 2000 Medtronic Navigation, Inc. System and method for image based sensor calibration
7835778, Oct 16 2003 Medtronic Navigation, Inc Method and apparatus for surgical navigation of a multiple piece construct for implantation
7835784, Sep 21 2005 Medtronic Navigation, Inc Method and apparatus for positioning a reference frame
7840253, Oct 17 2003 Medtronic Navigation, Inc Method and apparatus for surgical navigation
7853305, Apr 07 2000 Medtronic Navigation, Inc. Trajectory storage apparatus and method for surgical navigation systems
7881770, Mar 01 2000 Medtronic Navigation, Inc. Multiple cannula image guided tool for image guided procedures
7925328, Aug 28 2003 Medtronic Navigation, Inc. Method and apparatus for performing stereotactic surgery
7953471, May 03 2004 Medtronic Navigation, Inc. Method and apparatus for implantation between two vertebral bodies
7971341, Oct 17 2003 Medtronic Navigation, Inc. Method of forming an electromagnetic sensing coil in a medical instrument for a surgical navigation system
7974677, Jan 30 2003 Medtronic Navigation, Inc. Method and apparatus for preplanning a surgical procedure
7996064, Mar 23 1999 Medtronic Navigation, Inc. System and method for placing and determining an appropriately sized surgical implant
7998062, Mar 29 2004 Covidien LP Endoscope structures and techniques for navigating to a target in branched structure
8046052, Nov 19 2002 Medtronic Navigation, Inc. Navigation system for cardiac therapies
8057407, Oct 28 1999 Medtronic Navigation, Inc. Surgical sensor
8060185, Nov 19 2002 Medtronic Navigation, Inc. Navigation system for cardiac therapies
8074662, Oct 28 1999 Medtronic Navigation, Inc. Surgical communication and power system
8105339, Dec 12 1997 Sofamor Danek Holdings, Inc. Image guided spinal surgery guide system and method for use thereof
8112292, Apr 21 2006 Medtronic Navigation, Inc Method and apparatus for optimizing a therapy
8165658, Sep 26 2008 Medtronic, Inc Method and apparatus for positioning a guide relative to a base
8175681, Dec 16 2008 Medtronic Navigation Inc. Combination of electromagnetic and electropotential localization
8200314, Jan 27 1993 British Telecommunications public limited company Surgical navigation
8239001, Oct 17 2003 Medtronic Navigation, Inc Method and apparatus for surgical navigation
8271069, Oct 17 2003 Medtronic Navigation, Inc. Method and apparatus for surgical navigation
8290572, Oct 28 1999 Medtronic Navigation, Inc. Method and system for navigating a catheter probe in the presence of field-influencing objects
8320653, Jun 14 2000 Medtronic Navigation, Inc. System and method for image based sensor calibration
8359730, Oct 17 2003 Medtronic Navigation, Inc. Method of forming an electromagnetic sensing coil in a medical instrument
8401616, Nov 19 2002 Medtronic Navigation, Inc. Navigation system for cardiac therapies
8452068, Jun 06 2008 Covidien LP Hybrid registration method
8467589, Jun 06 2008 Covidien LP Hybrid registration method
8467851, Sep 21 2005 Medtronic Navigation, Inc. Method and apparatus for positioning a reference frame
8467853, Nov 19 2002 Medtronic Navigation, Inc. Navigation system for cardiac therapies
8473032, Jun 03 2008 Covidien LP Feature-based registration method
8494613, Aug 31 2009 Medtronic, Inc. Combination localization system
8494614, Aug 31 2009 Regents of the University of Minnesota; Medtronic, Inc. Combination localization system
8548565, Oct 28 1999 Medtronic Navigation, Inc. Registration of human anatomy integrated for electromagnetic localization
8549732, Oct 17 2003 Medtronic Navigation, Inc. Method of forming an electromagnetic sensing coil in a medical instrument
8611984, Apr 08 2009 Covidien LP Locatable catheter
8634897, Apr 07 2000 Medtronic Navigation, Inc. Trajectory storage apparatus and method for surgical navigation systems
8644907, Oct 28 1999 Medtronic Navigaton, Inc. Method and apparatus for surgical navigation
8660635, Sep 29 2006 Medtronic, Inc Method and apparatus for optimizing a computer assisted surgical procedure
8663088, Sep 15 2003 Covidien LP System of accessories for use with bronchoscopes
8696548, Apr 17 2002 Covidien LP Endoscope structures and techniques for navigating to a target in branched structure
8696685, Apr 17 2002 Covidien LP Endoscope structures and techniques for navigating to a target in branched structure
8706185, Oct 16 2003 Medtronic Navigation, Inc. Method and apparatus for surgical navigation of a multiple piece construct for implantation
8731641, Dec 16 2008 Medtronic Navigation, Inc. Combination of electromagnetic and electropotential localization
8764725, Feb 09 2004 Covidien LP Directional anchoring mechanism, method and applications thereof
8768437, Aug 20 1998 Sofamor Danek Holdings, Inc. Fluoroscopic image guided surgery system with intraoperative registration
8838199, Apr 04 2002 Medtronic Navigation, Inc. Method and apparatus for virtual digital subtraction angiography
8845655, Apr 20 1999 Medtronic Navigation, Inc. Instrument guide system
8905920, Sep 27 2007 Covidien LP Bronchoscope adapter and method
8932207, Jul 10 2008 Covidien LP Integrated multi-functional endoscopic tool
9055881, May 01 2005 Covidien LP System and method for image-based alignment of an endoscope
9089261, Sep 15 2003 Covidien LP System of accessories for use with bronchoscopes
9113813, Apr 08 2009 Covidien LP Locatable catheter
9117258, Jun 03 2008 Covidien LP Feature-based registration method
9168102, Jan 18 2006 Medtronic Navigation, Inc Method and apparatus for providing a container to a sterile environment
9271803, Jun 06 2008 Covidien LP Hybrid registration method
9504530, Oct 28 1999 Medtronic Navigation, Inc. Method and apparatus for surgical navigation
9575140, Apr 03 2008 Covidien LP Magnetic interference detection system and method
9597154, Sep 29 2006 Medtronic, Inc. Method and apparatus for optimizing a computer assisted surgical procedure
9642514, Apr 17 2002 Covidien LP Endoscope structures and techniques for navigating to a target in a branched structure
9659374, Jun 03 2008 Covidien LP Feature-based registration method
9668639, Sep 27 2007 Covidien LP Bronchoscope adapter and method
9675424, Jun 04 2001 Surgical Navigation Technologies, Inc. Method for calibrating a navigation system
9757087, Feb 28 2002 Medtronic Navigation, Inc. Method and apparatus for perspective inversion
9867721, Jan 30 2003 Medtronic Navigation, Inc Method and apparatus for post-operative tuning of a spinal implant
9986895, Sep 27 2007 Covidien LP Bronchoscope adapter and method
RE39133, Sep 24 1997 Medtronic Navigation, Inc Percutaneous registration apparatus and method for use in computer-assisted surgical navigation
RE40852, Jun 14 1995 SURGICAL NAVIGATION TECHNOLOGIES, INC Method and system for navigating a catheter probe
RE41066, Jun 14 1995 SURGICAL NAVIGATION TECHNOLOGIES, INC Method and system for navigating a catheter probe
RE42194, Sep 24 1997 Medtronic Navigation, Inc. Percutaneous registration apparatus and method for use in computer-assisted surgical navigation
RE42226, Sep 24 1997 Medtronic Navigation, Inc. Percutaneous registration apparatus and method for use in computer-assisted surgical navigation
RE43328, Nov 20 1997 Medtronic Navigation, Inc Image guided awl/tap/screwdriver
RE43750, Jun 14 1995 Medtronic Navigation, Inc. Method for navigating a catheter probe
RE43952, Oct 05 1989 Medtronic Navigation, Inc. Interactive system for local intervention inside a non-homogeneous structure
RE44305, Sep 24 1997 Medtronic Navigation, Inc. Percutaneous registration apparatus and method for use in computer-assisted surgical navigation
RE46409, Nov 20 1997 Medtronic Navigation, Inc. Image guided awl/tap/screwdriver
RE46422, Nov 20 1997 Medtronic Navigation, Inc. Image guided awl/tap/screwdriver
Patent Priority Assignee Title
3360665,
3485088,
3821834,
4365515, Sep 15 1980 MONITEK TECHNOLOGIES, INC , A CORP OF DE; MONITEK TECHNOLOGIES, INC Ultrasonic sensing
4424465, May 15 1980 Toray Industries, Inc. Piezoelectric vibration transducer
4446395, Dec 30 1981 PICKER INTERNATIONAL, INC Short ring down, ultrasonic transducer suitable for medical applications
4615330, Sep 05 1983 Olympus Optical Co., Ltd. Noise suppressor for electronic endoscope
4656870, Jul 30 1984 Kraftwerk Union Aktiengesellschaft Ultrasonic testing device
4708127, Oct 24 1985 WELLS FARGO BANK, NATIONAL ASSOCIATION FLAIR INDUSTRIAL PARK RCBO Ultrasonic generating system with feedback control
///////////
Executed onAssignorAssigneeConveyanceFrameReelDoc
Feb 02 1988Intra-Sonix, Inc.(assignment on the face of the patent)
Feb 02 1988MARTINELLI, MICHAEL A INTRA-SONIX, INC , A CORP OF DEASSIGNMENT OF ASSIGNORS INTEREST 0048340728 pdf
May 19 1995INTRA-SONIX, INC ENTERPRISE MEDICAL TECHNOLOGIES, INC ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS 0078240802 pdf
Jun 11 2001ENTERPRISE MEDICAL TECHNOLOGIES, INC ABLECO FINANCE LLC, AS AGENTSECURITY INTEREST SEE DOCUMENT FOR DETAILS 0119670879 pdf
May 31 2002ABLECO FINANCE LLCENTERPRISE MEDICAL TECHNOLOGIES, INC , A MASSACHUSETTS CORPORATIONTERMINATION AND RELEASE OF SECURITY INTEREST0130890838 pdf
May 31 2002ABLECO FINANCE LLCARTHUR D LITTLE ENTERPRISES, INC , A MASSACHUSETTS CORPORATIONTERMINATION AND RELEASE OF SECURITY INTEREST0130890838 pdf
May 31 2002ABLECO FINANCE LLCARTHUR D LITTLE, INC TERMINATION AND RELEASE OF SECURITY INTEREST0130890838 pdf
May 31 2002ABLECO FINANCE LLCCAMBRIDGE CONSULTANTS, LTD , A UNITED KINGDOM CORPORATIONTERMINATION AND RELEASE OF SECURITY INTEREST0130890838 pdf
Jul 31 2003Winchester Development AssociatesSURGICAL NAVIGATION TECHNOLOGIES, INC ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS 0157660865 pdf
Jul 31 2003MARTINELLI, MICHAEL A SURGICAL NAVIGATION TECHNOLOGIES, INC ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS 0157660865 pdf
Dec 22 2004ENTERPRISE MEDICAL TECHNOLOGY AND DEHON, INC SURGICAL NAVIGATION TECHNOLOGIES, INC ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS 0157660865 pdf
Date Maintenance Fee Events
Mar 03 1993M183: Payment of Maintenance Fee, 4th Year, Large Entity.
Mar 22 1993ASPN: Payor Number Assigned.
Feb 25 1997M184: Payment of Maintenance Fee, 8th Year, Large Entity.
Mar 27 2001REM: Maintenance Fee Reminder Mailed.
Sep 02 2001EXP: Patent Expired for Failure to Pay Maintenance Fees.


Date Maintenance Schedule
Sep 05 19924 years fee payment window open
Mar 05 19936 months grace period start (w surcharge)
Sep 05 1993patent expiry (for year 4)
Sep 05 19952 years to revive unintentionally abandoned end. (for year 4)
Sep 05 19968 years fee payment window open
Mar 05 19976 months grace period start (w surcharge)
Sep 05 1997patent expiry (for year 8)
Sep 05 19992 years to revive unintentionally abandoned end. (for year 8)
Sep 05 200012 years fee payment window open
Mar 05 20016 months grace period start (w surcharge)
Sep 05 2001patent expiry (for year 12)
Sep 05 20032 years to revive unintentionally abandoned end. (for year 12)